It has been known that the gene of an α1→6 fucosyltransferease (FUT8), which transfers an L-fucose residue to the reducing terminal N-acetylglucosamine of the N-linked glycan via an α1→6-linkage to form core fucosylation, expresses in accordance with the canceration of hepatocytes. The hepatocellular carcinoma is currently detected by lectin affinity electrophoresis using Lens culinaris agglutinin (LCA) having an affinity to core-fucosylated mono- and bi-antennary N-glycans.
Antibody-dependent cellular cytotoxicity (hereinafter referred to as an ADCC activity) is one of the immune functions owned by humans. The ADCC activity is an activity through which leukocytes such as natural killer cells and monocytes kill target cells such as cancer cells via antibodies. The ADCC activity has a relation with the antitumor mechanism by the antibody medical drug such as Herceptin as a humanized antibody (a therapeutic agent for metastatic breast cancer) and Rituxan as a chimeric antibody (a therapeutic agent for non-Hodgkin's lymphoma) (Non-patent Publication 1) against tumors. When these antibody medical drugs have a low ADCC activity, the need is caused to administer a high amount of the antibody medical drug, which consequently causes problems such as an increased cost and a side effect (e.g., infection due to an immune compromise).
The ADCC activity is different by a difference of 50 to 100 times between an antibody to which α1→6 L-fucose is transferred and an antibody to which α1→6 L-fucose is not transferred (Non-patent Publication 2). If an antibody to which α1→6 L-fucose is not transferred can be obtained, the antibody preparation having a high ADCC activity can be provided.
Conventionally, in addition to LCA, other core fucose-binding lectins have been known such as Pisum sativum agglutinin (PSA), Aleuria aurantia lectin (AAL), Narcissus pseudonarcissus agglutinin (NPA), Vicia faba agglutinin (VFA), and Aspergillus oryzae lectin (AOL) for example (Patent Publications 1 to 5).    Non-patent Publication 1: Clynes R A et al., Inhibitory Fc receptors modulate in vivo cytoxicity against tumor targets. NATURE MED 2000 APR; 6(4): 443-446    Non-patent Publication 2: Toyohide Shinkawa et al., The absence of L-fucose but not the presence of galactose or bisecting N-acetyl glucosamine of human IgG1 complex-type oligosaccharides shows the critical role of enhancing antibody-dependent cellular cytotoxicity. J Biol. Chem. 2003 Jan. 31; 278(5): 3466-73. Epub 2002 Nov. 8.    Patent Publication 1: WO2002/030954    Patent Publication 2: WO2003/084569    Patent Publication 3: Example of Japanese Unexamined Patent Application Publication No. H02-083337    Patent Publication 4: Example 5 of Japanese Unexamined Patent Application Publication No. 2002-112786    Patent Publication 5: Japanese Unexamined Patent Application Publication No. 2007-161633